Synchronization is the act of aligning events in time. Synchronization in communication systems, such as those that distribute digital video, is used for accurate transmission and reception of communication data, precise buffer management, and distortion-free signal switching.
Synchronization is a central issue for many communication systems and has many variations. A global communication system often requires synchronization between geographically dispersed sites. Each site often requires synchronization between individual equipment chassis within a site. Each chassis often requires synchronization between individual modules within the chassis. Each of these levels of a synchronization hierarchy, require different tradeoffs in terms of precision, flexibility, robustness, and cost.
Maintaining synchronization at any level is important to ensure the accuracy and timeliness of delivery of data in a communication system. For example, in the real time delivery of an MPEG-2 stream, the communication system should be able to withstand various perturbations to synchronizing information as well as the failure or removal of components within the system.
Traditional approaches to providing robust synchronization have not been able to ensure that synchronization is maintained during perturbations to the communication system. Traditional approaches require multiple clocks or global counters, thus adding to the complexity and cost of the communication system. Thus, there is a need for a flexible and low cost solution to the problem of robust synchronization. The present invention addresses this need.